State the range of wavelengths Delta lambda for the red yell

State the range of wavelengths (Delta lambda) for the red, yellow and green colors. Find the material band gap energy (Eg) required to make a green LED. Compute the maximum wavelength that can be detected by a photodiode made from Si and Ge. If the LDR area is increased what effect will it have on its R value? Explain briefly why the LED power decreases at high temperature? The LED driver circuit of Fig. 1 is used to drive a desired forward current through the LED by varying R_2, R_1 or R_E. Perform DC analysis to derive and expression for I_f. Design circuit to set a current level of 10mA. (Assume BJT beta = 100). As temperature increases, LED power decreases, explain how R_E can be used to make correction and increase LED power. Explain how a thermistor could be used to replace one of the R\'s to maintain constant power level. Select one application and design an optical measurement system for it: System that can count milk bottles on a moving belt or System that can measure short distance (0 to 20 cm). Draw the system and identify all components and circuits required. Describe the system operation Discuss all sources of errors and recommend corrections.

Solution

There are too many questions, Question 2 you can look for it in any textbook. I answered the question 3, here are links of the photos from my notebook:

1- https://drive.google.com/open?id=0B5Kioj2EbCtBcnhRZkhpbUFsVWc

2- https://drive.google.com/open?id=0B5Kioj2EbCtBY0lEU0dhTDdyNG8

3- https://drive.google.com/open?id=0B5Kioj2EbCtBU2JzV0ZmbjBjZFE

4- https://drive.google.com/open?id=0B5Kioj2EbCtBazR4bXBxcVMxa00

5- https://drive.google.com/open?id=0B5Kioj2EbCtBNncxRkJxM3hObW8

Regards,

Federico.